Approximately 30% or more of the world's population wears prescription eyeglasses to correct their eyesight. Prescription eyeglasses with corrective lenses can be used to correct refractive errors in human eyes by modifying an effective focal length of an eye lens. Corrective lenses can be effective for alleviating effects of conditions such as near-sightedness (myopia), far-sightedness (hyperopia), astigmatism, presbyopia, and the like. Presbyopia is a common condition in older persons that can be caused by an eye's crystalline lens losing elasticity. Loss of elasticity due to presbyopia can progressively reduce an ability of the eye's crystalline lens to focus on objects close to the eye.
An individual who wears prescription lenses may have to rely on solutions such as prescription sunglasses, clip-on sunglasses over the prescription glasses, and wraparound sun shields attached to the prescription glasses to protect his/her eyes from harmful ultraviolet rays. Carrying both normal prescription eyeglasses and prescription sunglasses can be inconvenient and expensive. Also, using clip-on sunglasses or a wraparound sun shield may look unnatural or unfashionable and may be inconvenient.